/*
 * Copyright (C) 2015 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.util.concurrent.NullnessCasts.uncheckedCastNullableTToT;

/**
 * Emulation for InterruptibleTask in GWT.
 */
abstract class InterruptibleTask<T> implements Runnable
{

    @Override
    public void run()
    {
        T result = null;
        Throwable error = null;
        if (isDone())
        {
            return;
        }
        try
        {
            result = runInterruptibly();
        }
        catch (Throwable t)
        {
            error = t;
        }
        if (error == null)
        {
            // The cast is safe because of the `run` and `error` checks.
            afterRanInterruptiblySuccess(uncheckedCastNullableTToT(result));
        }
        else
        {
            afterRanInterruptiblyFailure(error);
        }
    }

    abstract boolean isDone();

    abstract T runInterruptibly() throws Exception;

    abstract void afterRanInterruptiblySuccess(T result);

    abstract void afterRanInterruptiblyFailure(Throwable error);

    final void interruptTask()
    {
    }

    abstract String toPendingString();
}
